mirror of
https://github.com/bevyengine/bevy
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39c68e3f92
# Objective
Spatial audio was heroically thrown together at the last minute for Bevy
0.10, but right now it's a bit of a pain to use -- users need to
manually update audio sinks with the position of the listener / emitter.
Hopefully the migration guide entry speaks for itself.
## Solution
Add a new `SpatialListener` component and automatically update sinks
with the position of the listener and and emitter.
## Changelog
`SpatialAudioSink`s are now automatically updated with positions of
emitters and listeners.
## Migration Guide
Spatial audio now automatically uses the transform of the `AudioBundle`
and of an entity with a `SpatialListener` component.
If you were manually scaling emitter/listener positions, you can use the
`spatial_scale` field of `AudioPlugin` instead.
```rust
// Old
commands.spawn(
SpatialAudioBundle {
source: asset_server.load("sounds/Windless Slopes.ogg"),
settings: PlaybackSettings::LOOP,
spatial: SpatialSettings::new(listener_position, gap, emitter_position),
},
);
fn update(
emitter_query: Query<(&Transform, &SpatialAudioSink)>,
listener_query: Query<&Transform, With<Listener>>,
) {
let listener = listener_query.single();
for (transform, sink) in &emitter_query {
sink.set_emitter_position(transform.translation);
sink.set_listener_position(*listener, gap);
}
}
// New
commands.spawn((
SpatialBundle::from_transform(Transform::from_translation(emitter_position)),
AudioBundle {
source: asset_server.load("sounds/Windless Slopes.ogg"),
settings: PlaybackSettings::LOOP.with_spatial(true),
},
));
commands.spawn((
SpatialBundle::from_transform(Transform::from_translation(listener_position)),
SpatialListener::new(gap),
));
```
## Discussion
I removed `SpatialAudioBundle` because the `SpatialSettings` component
was made mostly redundant, and without that it was identical to
`AudioBundle`.
`SpatialListener` is a bare component and not a bundle which is feeling
like a maybe a strange choice. That happened from a natural aversion
both to nested bundles and to duplicating `Transform` etc in bundles and
from figuring that it is likely to just be tacked on to some other
bundle (player, head, camera) most of the time.
Let me know what you think about these things / everything else.
---------
Co-authored-by: Mike <mike.hsu@gmail.com>
105 lines
3 KiB
Rust
105 lines
3 KiB
Rust
//! Shows how to create a custom [`Decodable`] type by implementing a Sine wave.
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use bevy::audio::AddAudioSource;
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use bevy::audio::AudioPlugin;
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use bevy::audio::Source;
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use bevy::prelude::*;
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use bevy::reflect::TypePath;
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use bevy::utils::Duration;
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// This struct usually contains the data for the audio being played.
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// This is where data read from an audio file would be stored, for example.
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// Implementing `TypeUuid` will automatically implement `Asset`.
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// This allows the type to be registered as an asset.
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#[derive(Asset, TypePath)]
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struct SineAudio {
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frequency: f32,
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}
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// This decoder is responsible for playing the audio,
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// and so stores data about the audio being played.
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struct SineDecoder {
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// how far along one period the wave is (between 0 and 1)
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current_progress: f32,
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// how much we move along the period every frame
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progress_per_frame: f32,
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// how long a period is
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period: f32,
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sample_rate: u32,
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}
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impl SineDecoder {
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fn new(frequency: f32) -> Self {
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// standard sample rate for most recordings
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let sample_rate = 44_100;
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SineDecoder {
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current_progress: 0.,
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progress_per_frame: frequency / sample_rate as f32,
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period: std::f32::consts::PI * 2.,
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sample_rate,
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}
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}
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}
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// The decoder must implement iterator so that it can implement `Decodable`.
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impl Iterator for SineDecoder {
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type Item = f32;
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fn next(&mut self) -> Option<Self::Item> {
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self.current_progress += self.progress_per_frame;
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// we loop back round to 0 to avoid floating point inaccuracies
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self.current_progress %= 1.;
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Some(f32::sin(self.period * self.current_progress))
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}
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}
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// `Source` is what allows the audio source to be played by bevy.
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// This trait provides information on the audio.
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impl Source for SineDecoder {
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fn current_frame_len(&self) -> Option<usize> {
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None
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}
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fn channels(&self) -> u16 {
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1
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}
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fn sample_rate(&self) -> u32 {
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self.sample_rate
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}
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fn total_duration(&self) -> Option<Duration> {
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None
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}
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}
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// Finally `Decodable` can be implemented for our `SineAudio`.
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impl Decodable for SineAudio {
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type Decoder = SineDecoder;
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type DecoderItem = <SineDecoder as Iterator>::Item;
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fn decoder(&self) -> Self::Decoder {
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SineDecoder::new(self.frequency)
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}
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}
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fn main() {
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let mut app = App::new();
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// register the audio source so that it can be used
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app.add_plugins(DefaultPlugins.set(AudioPlugin {
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global_volume: GlobalVolume::new(0.2),
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..default()
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}))
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.add_audio_source::<SineAudio>()
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.add_systems(Startup, setup)
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.run();
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}
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fn setup(mut assets: ResMut<Assets<SineAudio>>, mut commands: Commands) {
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// add a `SineAudio` to the asset server so that it can be played
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let audio_handle = assets.add(SineAudio {
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frequency: 440., //this is the frequency of A4
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});
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commands.spawn(AudioSourceBundle {
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source: audio_handle,
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..default()
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});
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}
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